Influence of nitrogen substitution on the electronic band structure of poly(peri-naphthalene)

The electronic valence band structure of PPDAN, a chemical modification of poly(peri-naphthalene) where the central two carbon atoms of each naphthalene unit cell are substituted by nitrogen atoms, is theoretically investigated using the nonempirical VEH method. VEH calculations predict that PPDAN is a semiconductor with a small bandgap of 0.64 eV when a planar D2h structure is assumed for the unit cell. The bandgap increases to 1.3 – 1.6 eV when the more stable C2v and C2h structures are used.